Internal combustion engines are utilized for a wide variety of situations from transportation to stationary power generation. Some applications such as in stationary power generation will have the engine running at a single speed which allows the engine to be optimized to that situation. Other situations such as in highway transportation provide situations from acceleration to constant speed cruising to idling. Each of these require substantially different power requirements and often different speed requirements. A conventional engine cannot be optimized to operate in any of these conditions as it must operate in all the conditions. Compromises must be made to allow this flexibility.
An engine must be designed with enough combustion chamber capacity to produce the required power which dictates a volume of air which needs to pass through the engine to fill the combustion chamber capacity. When an engine is idling or is cruising at a constant speed, the same volume of air will pass through the engine during each revolution of the engine. As the engine must fire or ignite fuel with the air, enough fuel must enter the combustion chamber to allow this ignition.
One approach to eliminating this excess of fuel required has been done in some engines which simply block the air supply to some of the cylinders. In the case of an 8 cylinder engine, 2 or 4 of the cylinders have been blocked to theoretically cut the air and fuel volume by up to 50%. Other realities will limit this optimal result. Whereas this provided a better fuel economy, it caused problems with the resultant irregular heat patterns in the engines. It additionally provides only step changes which minimized the opportunity of optimization.
Changing the gearing between the engine and the wheels to run the engine as slowly as possible has provided some fuel efficiency. In the cruising situation at a normal driving speed the engine operates at a higher more efficient pressure than would happen if the engine were allowed to run faster in similar conditions. If more power is needed for acceleration at the same driving speed, the transmission can be downshifted to allow the higher engine rpm. This has limited advantage is some diesel engines as they optimally run at a specific RPM.
Another problem with internal combustion engines is that they are fuel grade sensitive. Changes in fuel from gasoline to diesel fuel and from low octane to high octane fuel dictate different compression ratios in engines. The compression ratio is the size of the combustion chamber at its largest volume to the size of the combustion chamber at the smallest volume. This is generally when the rod journal or eccentric on the crankshaft is at the bottom of a rotation and when the crankshaft rod journal or eccentric is at the top of a rotation. The typical compression ratios of gasoline type engines are in the range of 8-11/1 and for diesel engines are in the range of 14-20/1.
The changes in these compression ratios is so significant that the gasoline type engines have ignition based upon a spark plug within the cylinder initiating the ignition. On a diesel engine the more intense pressure and resulting temperature generated by the rapid compression causes the fuel to explode without a spark plug.
Although the need for a variable displacement engine has long been recognized, there have been no suitable solutions provided prior to this invention for an internal combustion engine with an infinitely variable displacement which can be changed while the engine is in operation as well as changing the compression ratio of the engine.